In the Linux kernel, the following vulnerability has been resolved:
mptcp: cope racing subflow creation in mptcprcvspace_adjust
Additional active subflows - i.e. created by the in kernel path manager - are included into the subflow list before starting the 3whs.
A racing recvmsg() spooling data received on an already established subflow would unconditionally call tcpcleanuprbuf() on all the current subflows, potentially hitting a divide by zero error on the newly created ones.
Explicitly check that the subflow is in a suitable state before invoking tcpcleanuprbuf().